1. Field of the Invention
The present invention relates in general to automotive seats and, more particularly, to automotive seats of a type which is equipped at both side of a seatback thereof with pivotal side supports.
2. Description of the Prior Art
In order to clarify the task of the present invention, two conventional automotive seats of the above-mentioned type will be outlined with reference to FIGS. 6 to 9 of the accompanying drawings.
In FIGS. 6 and 7, there is shown a seatback of one conventional seat, which comprises a seatback proper 100, a headrest 200 mounted on the seatback proper 100 in a known manner, and side supports 1a and 1b pivotally connected to respective side portions of the seatback proper 100. Each side support 1a or 1b has a pivoting axis 2 a or 2b about which the same is pivotal relative to the seatback proper 100. As is seen from FIG. 7, the thickness of each side support 1a or 1b gradually decreases with increase of height of the same. Designated by numeral 3 is a front surface of the side support 1a or 1b, which is thus inclined with respect to the pivoting axis 2a or 2b. Designated by reference "D" is an imaginary axis which is perpendicular to an upper surface of a seat cushion 300. Upon proper sitting of a person on the seat, the axis of the body of the person coincides with the imaginary axis "D".
In FIGS. 8 and 9, there is shown a seatback of the other conventional seat, which, similar to the above-mentioned one, comprises a seatback proper 100, a headrest 200, and side supports 5a and 5b. As is seen from FIG. 8, the side supports 5a and 5b are so arranged that their respective pivoting axes 6a and 6b are inclined relative to the imaginary axis "D". That is, the distance "L" between the two axes 6a and 6b gradually decreases with increase of height of them.
However, due to their inherent constructions, the above-mentioned two seatbacks have the following drawbacks.
That is, in the former one, even when the side supports 1a and 1b are raised to assume their operative or holding positions, the upper portion of each side support 1a or 1b fails to achieve a sufficient holding performance because of a considerable distance which is inevitably remained between the upper portion of the side support 1a or 1b and the axis "D" of the seat occupant's body.
In the latter one, a sufficient holding performance of the upper portion of each side support 1a or 1b is obtained. However, the upper portions of the side supports 1a and 1b tend to apply the seat occupant with uncomfortable pressure because of a shortened distance which is inevitably remained between the upper portion of the side support 5a or 6a and the axis "D" of the seat occupant's body.